Cellular communication networks are increasing significantly in the number of subscribers and the traffic volume they handle. Especially increasing is the data traffic over these communication networks. The introduction of the so-called third generation networks will even accelerate this increase, for example by multi media applications. Operators are looking for effective solutions to handle this increased traffic within their networks. As a variety of different protocols, defining data connection parameters, are in use, adaptations are to be performed within communication networks. These adaptations allow data connections between users whose data are transmitted according to different protocols, for example a fixed network subscriber using an ISDN (Integrated Services Digital Network) protocol and a mobile subscriber using a GSM (Global System for Mobile communication) protocol.
It is state of the art, that protocols used for the transmission of data from a mobile user are adapted by interworking functions. To reduce the number of interworking functions within a communication network, the concept of shared interworking functions has been introduced, for example in GSM networks. In U.S. Pat. No. 5,850,391, a possible implementation of an interworking function is described.
An access network consists at least of access nodes that manage the resources of the access network and provide the user with at least one mechanism to access the core network. Access networks include for example GSM base station subsystems or UMTS (Universal Mobile Telephony Systems) or UTRAN (Umts Terrestrial Radio Access Networks).
A core network consists at least of control nodes that provide support for the network features and telecommunication services. The support provided may include for example the management of user location information and, the control of network features and services the transfer mechanisms for signalling and for payload.
Payload transmission resources are devices that are used for the transmission of payload data, for example interworking functions, transmission converter and routing devices.
A media gateway is a network node that comprises resources for the transmission of payload data. It can be part of the core network or is placed at the edge between core network and access network. For clarity reasons, in the following a media gateway is seen as part of a core network.
A gateway control node is a control node that contacts a home location register.
An interworking function comprises the protocol conversion functionality for data communication within a communication network or between communication networks. It can perform data rate adaptations, buffer data and terminates telecommunication network specific protocols. Some interworking functions also terminate transmission method protocols. Transmission methods are methods for the transmission of data designed for example according to the standards and recommendations for ATM (Asynchronous Transfer Mode), STM (Synchronous Transfer Mode), and IP (Internet Protocol).
Telecommunication networks include for example UMTS (Universal Mobile Telecommunication Systems), GSM (Global System for Mobile communications) and ISDN (Integrated Services Digital Network) networks.
A transmission converter terminates transmission method protocols, bridges data from one transmission method to another transmission method, performs readdressing, packing or unpacking, and transmission of data. A transmission converter can be implemented as a single device, for example as a stand-alone device or in a media gateway or a mobile services switching centre, or distributed, for example in a media gateway. Unlike interworking functions, transmission converters do not impact the protocol levels above a transmission method.
Routing devices are entities, within a media gateway including an incoming point of the media gateway and an outgoing point of said media gateway, that transmit payload data, perform the routing within the media gateway and convert data packages if necessary. If the payload transmission functionality is implemented within a mobile services switching centre MSC instead of a media gateway, routing devices are placed within said mobile services switching centre.
A parameter set describes a connection. For a GSM network, at least the following parameters are included in a parameter set: radio channel requirement, information transfer capability in the case that a UDI (Unrestricted Digital Interface) is used or other information transfer capability in the case that a RDI (Restricted Digital Information) is used, compression, NIRR (Negotiation of Intermediate Rate Requested), rate adaptation, other rate adaptation, sync/async, user rate, intermediate rate, connection element, acceptable channel coding and wanted air interface.
It is useful to include the following parameters:
Number of stop bits, maximum number of traffic channels, and user initiated modification indication.
The mentioned parameters are for example known from the standard GSM 04.08 version 5.6.2. released September 1997.
For an ISDN network the bearer capability as defined in the ITU-T recommendation Q.931, released March 1993, covers the parameter set.
It is a shortcoming of the state of the art that the usage of the interworking functions is performed in a way that does not allow to limit the number transcodings to a minimum number that is technically required.
It is an object of the invention to reduce the number of transcodings within a core network and to reduce the number of payload transmission resources linked into a payload transmission connection.